Question

A man can see vertical lines but he is unable to see the horizontal lines placed at the same distance. What type of lens should he use?
A) Convex Lens
B) Concave lens
C) Cylindrical lens
D) Rectangular lens

Answer 1

We have to find out the problem the man is suffering from. The man is suffering from Astigmatism. It is a common vision problem that is caused by a specific error in the shape of the cornea. To cure astigmatism we need a lens that has at least one non spherical shape.

Completed step by step solution:
To cure this type of problems there are many corrective medical treatments available. The least expensive and most easy of them is to wear a lens over your eye. Astigmatism is caused when the light is more bent in one direction than the other. It is very difficult for a person to focus, so a lens can correct the degree of bent coming to the eye and hence the man can focus easily. Here, we have been given four options, out of the four options the two options that are convex lens and concave lens are ruled out because they are used for shortsightedness and farsightedness. The fourth option i.e. the rectangular lens is used in camera and for photography purposes, so it is automatically ruled out. The third option that is the cylindrical lens is a lens with at least one surface that is not in the spherical shape and that is what is required to correct astigmatism.

Final Answer: Option “3” is correct. The man should be using a cylindrical lens to correct his vision.

Note: Here one needs to define the problem the man is suffering and then explain about effects or difficulties that the man faces while having that problem and then provide a solution mentioning about the lens that is most suitable to cure the problem and also explain about the working of the lens in curing the problem.